1. Field of the Invention
The present invention relates to low voltage electrical apparatus, and more particularly, to a protection module for control and protective switching device.
2. The Related Art
A control and protective switching device is a switching device that can be automatically controlled or manually controlled, and has or does not have a local manual operation apparatus. A control and protective switching device can switch on, bear or break a current under a normal condition, including a current under a specified overload condition. A control and protective switching device can also switch on, bear within a specified time and break a current under an abnormal condition, such as a short circuit current. That is, a control and protective switching device integrates the functions of a breaker, a contactor and a thermal relay.
A control and protective switching device is generally consisted of a protection module/circuit and electrical apparatuses that are electrically connected to the protection module/circuit. The electrical apparatuses include housings, contact arc extinguishing systems, operation mechanisms, control electromagnets, trip electromagnets, mutual inductors and electronic component boards, etc.
Currently, the “Schneider Tesys U” series control and protective switching devices have three types: Multifunctional type, Advanced type and Basic type. Only the protection module of the Multifunctional type has a control power supply loop and an auxiliary power supply loop, and the additional functions, such as the communication function can be achieved only when the control power supply loop and the auxiliary power supply loop are connected simultaneously. The protection modules of the Advanced type and Basic type only have a control power supply loop. A protection module having only a control power supply loop has the following disadvantages: when a load that starts frequently is accessed to the control and protective switching device, frequent on-off of the control power supply results in frequent on-off of the circuit units within the protection module, which will cause considerable current impact injury to the circuit units, especially to chips, Field Effect Transistors (FETs), and capacitors. The service lives of the elements are thus influenced and the service life of the control and protective switching device is decreased.
Further, the protection module of some control and protective switching device uses a structure that the control power supply and the auxiliary power supply are independent, that is, the control power supply and the auxiliary power supply each has a pair of connection terminals. When the auxiliary power supply works under normal working voltage, a user may connect a control button externally and control the status of the control power supply through manipulation of the control button, so as to achieve the control of an electromagnet. The disadvantage of this design is that the user must connect the control power supply and the auxiliary power supply simultaneously so as to achieve normal work of switch device, which to some extent increases the complexity of usage and the workload of connection.